Source : Webster's Revised Unabridged Dictionary (1913)

Definite \Def"i*nite\, a. [L. definitis, p. p. of definire: cf.
   F. d['e]fini. See {Define}.]
   1. Having certain or distinct; determinate in extent or
      greatness; limited; fixed; as, definite dimensions; a
      definite measure; a definite period or interval.

            Elements combine in definite proportions. --Whewell.

   2. Having certain limits in signification; determinate;
      certain; precise; fixed; exact; clear; as, a definite
      word, term, or expression.

   3. Determined; resolved. [Obs.] --Shak.

   4. Serving to define or restrict; limiting; determining; as,
      the definite article.

   {Definite article} (Gram.), the article the, which is used to
      designate a particular person or thing, or a particular
      class of persons or things; -- also called a definitive.
      See {Definitive}, n. - 

   {Definite inflorescence}. (Bot.) See {Determinate
      inflorescence}, under {Determinate}.

   {Law of definite proportions} (Chem.), the essential law of
      chemical combination that every definite compound always
      contains the same elements in the same proportions by
      weight; and, if two or more elements form more than one
      compound with each other, the relative proportions of each
      are fixed. Compare Law of multiple proportions, under
      {Multiple}.

Source : WordNet®

definite article
     n : a determiner (as `the' in English) that indicates
         specificity of reference